1. Field of the Invention
Semiconductor wafers are routinely carried in wafer carriers or "boats" during various stages of their manufacture. The invention relates to a handle and, more particularly, a means at the bottom of the handle for grabbing and securely holding the wafer carrier.
2. Description of the Prior Art
Semiconductor wafers are the basic material upon which integrated circuit (IC) die are manufactured. The wafers are most commonly composed of pure, monocrystalline silicon and are normally very thin and generally round. Silicon wafers typically are on the order of one millimeter thick and have been manufactured in diameters from two to ten inches. They are rather fragile and expensive and are made more fragile and more valuable by stages of the IC production process.
During processing, it is necessary that wafers be contained within a vehicle which protects the wafers from contact with undesirable foreign matter and from contacting each other. At the same time, the vehicle must allow the wafers to be exposed freely in various baths and processes and the vehicle must be able to endure those processes. Such vehicles are well known in the art as wafer "baskets", "carriers", or "boats" Wafer carriers are described in U.S. Pat. No. 3,939,973 to Wallestad and U.S. Pat. No. 3,961,877 to Johnson. Typically the carriers have upright sides with slots configured to hold and properly space the wafers. The slot bottoms are partially closed to stop the wafers. The tops of the carriers are open for good access. The ends and bottoms of the carriers are closed sufficiently to give strength and rigidity but are sufficiently open to bathe the wafers quickly when immersed and allow them to drain when removed. The carriers are typically manufactured of temperature and chemical resistant plastic such as polypropylene and Du Pont Company's "Teflon".TM. Wafer carriers for very high temperature applications are made of quartz.
Handles which may be conveniently and repeatedly attached and detached to such wafer carriers are highly desireable. They provide convenient means to transport the carriers and enable a handler to safely immerse and recover baskets from acid baths and various other processes. Handles representative of those used in semiconductor manufacture are described in U.S. Pat. Nos. 3,701,558 to Baker and 3,923,191 to Johnson. Compression of these handles will cause them to spread at their bases to receive and lock onto the carriers. Upward force, as is normal in carrying the handle and wafer carrier, causes the handle to press into the carrier and to enmesh the locking configuration of the handle legs into the receiving mechanism of the carrier. Handles, too, must be constructed of a material able to withstand very hot and/or corrosive conditions. The design and the material of the handle must cooperate so that the essential function is met and continues throughout the range of conditions to which the basket is subjected. Such handles are similar to those shown in FIG. 1.
The Semiconductor Equipment and Materials International (SEMI) Standards Program is an influential promulgater of standards for equipment used in the semiconductor industry throughout the United States, Asia, and Europe. SEMI standards have been widely adopted in the design of wafer carriers and SEMI specifications of automated usage fixtures for wafer carriers are the standard of the semiconductor manufacturing industry.
The object of this invention is the interconnection between the handle and the wafer carrier and, particularly, between the handle and the robotic fixtures of a SEMI standard wafer carrier. Carriers which will allow wafers to be transported and processed safely and routinely are well established in the art. Handles which allow baskets to be carried once a "lock" has been achieved, at room temperature, and without agitation or twisting movement are also available. There remains a need, however, for a mechanism which can be incorporated into handles otherwise conventional in the industry and which will reliably attach to and contain the mechanism of basket types conventional in the industry. A single failure which results in the destruction of a basket of wafers in an advanced state of manufacture could mean a loss measurable in thousands of dollars. Such losses have been known to occur, particularly in extreme conditions such as during an etching process when wafers, basket, and handle are subjected to hot acid. It is not uncommon for conventional locking devices to become pliable under such conditions and detach from the basket causing excessive etching and destruction of the wafer batch. The invention provides means of secure attachment of conventional handles and baskets, even when subjected to elevated temperatures and severe torque motion.